Hesitation in 5th gear @ ~3000rpm 65-75mph

[NotDave]

I can't seem to feel it in other gears but i know that my car is hesitating because it seems a lot slower compared to my other 240sx i used to own. it comes and goes. my gas mileage is not good, only 250-280 or so miles to the tank when i should be getting close to 330-350.

when it happens it feels like i don't have enough power at that gear. the best way i can describe it is like when you are in the wrong gear at the wrong speed. like you are in 5th gear and going only 30mph so it vibrates a little bit and makes that buzzing sound.

parts already replaced:plug wiresplugscaprotorfuel filterair filtero2 sensorcoolant temp sensor

car also passed smog with flying colors so emissions are good.

its driving me crazy. help

[Ninja Turtle]

clean out your maf. make sure its plugged in all the way etc.

does the car idle fine?

[NotDave]

thanks for the reply. car idles fine

maf is plugged in properly, ground to maf is also good. car revs fine, from what i've read when the maf fails people can't rev past a certain rpm, i can rev completely through all the gears.

whats the best why to clean the maf?

[rogoman]

Do an ECU code readout. If there's a fault code set, it might help you to diagnose the problem.

Also do compression test on all cylinders. If the compression is low across the board, then the power level and MPG will drop off.

[NotDave]

thank you for the reply. the ecu is not throwing any codes. i checked it twice.

as for compression..i need to check it. its the last thing i wanted to check because it would mean trouble for me lol.

edit: even when the problem comes and goes i should check compression? i assume compression is good if the problem is intermittent

[nightkid86]

To clean MAF use electical parts alcohol 99% iirc, they have it at radioshack

[NotDave]

any other ideas?

could it be a fuel delivery problem like fpr or injectors.

i already checked for vacuum leaks.

[AZhitman]

I'd look at fuel pressure (use an external gauge), ohm your injectors, and make sure you have good, hot, blue spark at each cylinder.

How did you check for vacuum leaks?

[NotDave]

i checked the ohm reading on my injectors. i pulled of the connections to all the injectors, car was off, key was in my pocket. put a meter to test the ohms.

from the front of the car to the back it read:

BACK/FIREWALL30382412FRONT/RADIATOR

im guessing my injectors need replacing? looks like the back three are out of spec? the best price i could find for injectors is 68 a piece after giving my core. im gonna go to ebay and get a set for like 20 shipped and hopefully they work, i figure if i spend 20-40 dollars on ebay its still cheaper than one injector at the store